Conventionally, to provide a wear-resistant property to a metal, there has been widely used a technique of forming a coating film made of other metal material, ceramics, or the like on the surface of the metal. In general, such metals with a wear-resistant coating film are used under a temperature environment in a range from room temperature to about 200° C., and in most cases, used in an environment where there is oil as a lubricant. However, oil cannot be used everywhere. For example, oil cannot be used in aircraft engines inside of which the temperature ranges from room temperature to as high as about 1000° C. For materials used in such environments, therefore, it is necessary to exploit the material's wear-resistant property that comes from the material's inherent strength and lubricating performance.
FIG. 12-1 shows an example in which a wear-resistant coating film is formed on an aircraft gas turbine engine as one example. FIG. 12-2 is an enlarged view of a low-pressure turbine blade 802 of a low-pressure turbine 801 in the gas turbine engine shown in FIG. 12-1. FIG. 12-3 is a further enlarged view of a portion 803 of the low-pressure turbine blade 802 shown in FIG. 12-2, and shows a situation that a wear-resistant material is welded to a portion, which is referred to as an interlocking portion 804, of the low-pressure turbine blade 802 where turbine blades are interconnected to each another. Practically, the low-pressure turbine blade 802 is used after the welded portion is made into a flat surface by grinding.
On the other hand, there are disclosed technologies for forming a wear-resistant coating film with methods other than the welding. For example, there is disclosed such a technology that a coating film made from an electrode material is formed by generating a pulsed discharge between a powder compact and a material subject to a treatment (see Patent document 1 and Patent document 2). These Patent document 1 and Patent document 2 teach to mix an oxide into an electrode to solve the problem of wear resistance in an intermediate temperature range that is a problem of the conventional coating film described above.
Patent document 1: International Publication No. WO 2004/029329 pamphlet
Patent document 2: International Publication No. WO 2005/068670 pamphlet
Patent document 3: International Publication No. WO 2004/011696 pamphlet